The present application relates to apparatuses and methods for satellite-based position determination.
Satellite-based position determining apparatuses are nowadays incorporated in a variety of different devices. For example, navigation systems, mobile phones or also some digital cameras have satellite-based position determining apparatuses incorporated to enable a determination of their position. The most commonly used satellite navigation system is GPS (Global Positioning System) provided by the USA. Other satellite navigation systems are GLONASS provided by Russia, the Galileo System currently under development by the European Community or COMPASS provided by China.
Such satellite-based position determining apparatuses may be operated under different conditions. For example, when used for navigation in a car, velocities are frequently about 100 km/h and may even reach over 200 km/h, which necessitates a corresponding update rate of the position to provide the required accuracy. On the other hand, in such outdoor uses the signal strength is comparatively high, but may still vary depending on whether the navigation occurs within a city or in open country. On the other hand, when a pedestrian uses a satellite-based position determining apparatus indoors, the speed involved is considerably slower (only some km/h), but the signal strength is usually lower.
Sometimes, a single satellite position determining apparatus may be used for both of the above-mentioned usages. For example, a GPS receiver in a mobile phone may be used both for car navigation (for example by using an appropriate holder) and indoors. Therefore, in some cases, the performance of such an apparatus may not be at the optimum for both kinds of usage.